1. Technical Field
This invention relates to an information reproducing apparatus having a time difference reproducing function for recording input video information by a predefined predetermined time on a record disk and also reproducing record video information recorded on the record disk back to the predetermined time at a maximum.
2. Related Art
Conventionally, in an information reproducing apparatus having a time difference reproducing function, for example, analog input video information by two hours is digitized to record the information on a hard disk which is a record disk and record information of the hard disk can be reproduced back to the two hours ago at a maximum.
By the way, with regard to movies and other video information, an illegal copy is inhibited for copyright protection and as a technique of that purpose, there is a macrovision specification and this is a technique of adding a copy guard signal to a burst interval of an analog video signal as described in Japanese Patent No. 2895629 or the Unexamined Japanese Patent Application No.2000-308006.
According to this specification, in case that a video signal attempts to be copied by a VCR (Video Cassette Recorder) of analog type, dummy synchronous signal and color burst signal along with the video signal are recorded on a videotape, so that the video signal cannot be reproduced normally and the illegal copy is prevented.
[Problems to be Solved]
On the other hand, in the case of the information reproducing apparatus having the time difference reproducing function described above, there is no apparatus for recording video information on a hard disk for the purpose of copying and a primary purpose is to reproduce the video information back to a certain time, so that it is desirable to be able to perform time difference reproduction even in the case of the analog input video information to which the copy guard signal like the macrovision described above is added.
In order to enable the time difference reproduction by the information reproducing apparatus having the time difference reproducing function even in the case of the analog input video information to which the copy guard signal is added thus, it is necessary to add a copy guard signal to the reproduced video information in order to prevent the illegal copy while erasing record information of the hard disk after the reproduction.
However, in the information reproducing apparatus of this kind, there is no apparatus for providing a function of adding the copy guard signal thus and in an information reproducing apparatus having a conventional time difference reproducing function, time difference reproduction of the analog input video information to which the copy guard signal is added cannot be performed.
By the way, in Japanese Patent No. 3128959 or the Unexamined Japanese Patent Application No. Hei6-70282, etc. besides Japanese Patent No. 2895629 or the Unexamined Japanese Patent Application No.2000-308006 described above, techniques of inhibiting an illegal copy are described, but these apparatus do not relate to an information reproducing apparatus having a time difference reproducing function as shown in the invention of the present application.